Catalytic desulfurization of gas oil



Patented Nov. 6, 1951 2,574,448 CATALYTIC DESULFURIZATION GAS OIL

Patrick Docksey and Frederick William Bertram Porter, Sunbury-on-Thames,England, assignors to Anglo-Iranian Oil Company Limited, London,England, a British joint-stock corpo-.

ration No Drawing.

Application June 21, 1949, Serial No. 100,538. In Great Britain June 24,1948 3 Claims. (Cl. 196-28) The invention relates to the catalyticdesulphurisation of petroleum distillates boiling within the gas oilrange.

It is known to desulphurise petroleum distillates by passing them inadmixture with hydrogen over a sulphur-resistant hydrogenation catalystat elevated temperature and elevated pressure, whereby organic sulphurcompounds present in the distillates are hydrogenated to form hydrogensulphide which can readily be removed from the treated distillates. Theprocess as normally carried out involves a nett consumption of hydrogenand the cost of supplying the hydrogen is a major factor in theeconomics of the process. Furthermore, in order to secure the necessarypartial pressure of hydrogen, it has generally been considered necessaryto operate at elevated pressure ranging from 500-1000 1b./sq. in. ormore, and a plant to withstand such pressures has to be made fromspecial steels which are comparatively expensive.

It is well known that the hydroforming process effects considerabledesulphurisation and at the same time produces hydrogen mainly bydehydrogenation of the naphthenes present. This process, however, isapplicable to a very limited class of feedstock and does not constitutean economic desulphurisation process in view of the fact that thereaction conditions are so severe that the catalyst has a very shortactive life, and needs to be regenerated at short intervals (forexample, of six hours), while the increased production of aromatics isin many cases undesirable.

The invention has among its objects to provide a process for thecatalytic desulphurisation of gas oils which can be carried out withoutthe use of hydrogen added from an external source. It is also an objectof the invention to enable such a process to be carried out at pressureslow enough to avoid the use of special pressure-resisting steels,thereby reducing the cost of the plant.

It has now been found that by careful control of the reaction conditionsand that by selecting.

a suitable catalyst, it is possible to effect desulphurisation of gasoils without adding hydrogen from an external source, the hydrogennecessary for the conversion of the sulphur in the feedstock intohydrogen sulphide being derived from the feedstock itself.

According to the invention, the desulphurisation of anaphthene-containing petroleum distillate boiling within the gas oilrange is effected by vapourising the distillate and passing it inadmixture with hydrogen over a catalyst which combines activity fordehydrogenation of naphthene molecules to aromatics, with activity forthe conversion of organically combined sulphur to hydrogen sulphide, andwhich is not poisoned as a catalyst by the presence ofsulphurcompounds,at a temperature and at a pressure suffl cient to effect the conversionof a considerable proportion of the sulphur contained'in the distillateinto hydrogen sulphide,and topr'oduc a hydrogen-rich gas mixture whichis separated from the treated feedstock and recycled to the reactionzone at a rate sufiicient to maintain the necessary partial pressure ofhydrogen therein 4 T It is believed that the reaction proceeds "bydehydrogenation of some of the na'phthenes to produce hydrogen in excessof that required to convert the combined s'ulphur'present into hydrogensulphide, and the reaction conditions must therefore be determinedhaving regard to any limiting conditions imposed by these two'reactions. Thus, there is a lower temperature of about 700 F. belowwhich little dehydrogena tion would occur and below which thereactionwould not be self-supporting in'hyd'rogenf This lower temperaturedepends to some extent on the sulphur content, and the higher thesulphur content, the higher the minimum" temperature necessary toprovide s'ufii'cient -hydrogen. At temperatures above about 800'F.','dehydrog'enaa tion occurs to such an extent that the productbecomes increasingly aromatic; Furthermore, at temperatures a ove 800 F.the oil-stream time is reduced. The preferred temperature of opera tionis to some extent dependent-upon the pressure employed, which ispreferably between 50 and 200 lb./sq. in., and lies within the range750-820" F. As the'pi'essure is increased, the minimum temperature....at which satisfactory dehydrogenation of the naphthenes can beobtained increases, and if at a fixed temperature the pressure issufiiciently increased. the reverse reaction of hydrogenation ofaromatics begins zone.

.phide content of the separated gas builds up to tures.

to occur. Thus, when operating at the higher pressures, it is preferable'to use higher tempera- Similarly it is desirable to avoid thecombination of high temperature and low pressure since such conditionslead to short on-stream time for satisfactory operation.

The preferred space velocity lies between 1 and 2 v./v./hr., while thepreferred recycle rate for the hydrogen-containing gases lies between2000 and 4000 c; f. b. In general, the higher gas recycle rates shouldbe em loyed at the lower space velocities in order to shorten theresidence time within the reactor.

Operating under the conditions above described, the gases separated bycooling the treated fraction at reaction pressure contains -80% byvolume or moreof hydro en and are continuously recycled to, thedesulphurisation It has been found that the hydrogen sulan equilibriumconcentration after which the gases-may be recycled. to thedesulphurisation zone without-furtherincrease inthe content of hydrogensulphide which is thereafter dissolved in the product until such time asit is depressurised. If desired, however, the 'hydrogen sul- .followingTables 1-11. 'lyst employed consisted of cobalt molybdate on alumina,the cobalt molybdate containing an ex- 01128. gas oil of Iranianoriginare. set out in the In each case, the cata phide may be removedfrom the gases by anyof '5 mess of molybdenum oxide, the usual methodsand the hydrogensulphi'defrablesile5 illustrate the effect of varyingthe free gas recycled to the desulphurisatiomwne. pressure within the.range 50l50 p. s. i. ga. at a The gases y be Submitted t .treatment in:constanttemperature of approximately 780 F., a known manner for inc eat p spacevelocity' of .the feedstock of 2 v./v./hr. and P 10 0 hydmgentherein, a by passage a gas recycle rate of 2000 c. f. b. It will benoted through an 011 w r- I o 'n s y' pthat increase of; pressure withinthe range 50-150 p y extraneous hydrogen to the'desulllhmisaflonp.'s.'i. gap'results in increased desulphurisation, zone when Start g te process as the gases-sepathe-residual sulphur being inverselyproportional rated from the treated jfraction may be allowed to thehydrogen partial pressure. Desulphurisato;huild.up;to.form.the recycle.gaS- 15 tiozrat 150 p.-s. i. ga. is.about'80% compared with Mona :thepcataiysts that may be 'used are w t-40% t 50 ;1 ga

Oxides-especially those Dime be apparent from a consideration of6th;roup. either alone (for-example chromium Tables '7, 3 and 6 that theeffect of-varying the oxidend tu nu p or vin admlxture temperaturewithin the range '760-800 F., with with: other sulphides oroxides(for'example pelthepressure,v Space velocity and gas recycle rateletswnsistmg of-twoipa'rtstungstensulphide and constant, is slight, withmaximum desulphurisaone part-nickel sulphide) ,or in combination withmmat 7 09151 other oxides or Su1phides (for exafmple" cobalt The net gasmake-decreaseswith increase in molybdateor'tmomolybdate) *or'mlxed with"or pressure and increases with increase in temperdeposited:on,,-a poroussupport such-as natural-'or aura pmmdbauxiteracfivmd 'Tables'8+11illustrate-the effect of varying the bauxltamay them spacevelocity-between 1.0.and 2.0 v./v./hr. and ofselves-beused-.as-catalysts. The preferred catavarying thegaszrecycleratelbetween 2000 and fi cobaltmolybda'te supported 4000 c.f..b. Over 100 rhrs.:on stream were posu na.

as; 1212.35.22:-iitfifi??? was; mixing powderedscobalt oxide,-molybdate..oxide t M and" alumina {and peneting with 1% graphiteresidual sulphur at 2.0 v/v./hr. was 0.4% w .a into fir"zpelletswhichawerethen treatedfor-two at It was 03% 2 fefdstock hoursat-550 .C.Thecatalystmay--also-be.preof 10% sulphur l the recycle pared byextrusion rate from 4000 to 2000 0.1!. b. has little or no ef-Anefiecmve cobalt-molybdate type catalyst was feet. at 2.0 v./v./hr. butresults in-a marked loss of prepared.bytheimpregnation,Oil-casted Indiandesulphurisation and gas make at 1.0 v./v./hr. bauxitewith-cobalt'molybdate solution, so that Appears that the most efiicientp a on is the'molybdenum t t, thematerial t m 40 at 1.0 v./v./hr.andj4000 c. f. b. an'd'the marked at 1000-F.wvas;3,6,% by.weight,whilepthe cobalt improvement at 1.0 v./v./hr. as compared withcontent'of the material stable at l000 was 2.0 v./v./hr. is surprisingin view of the fact that 1.0% weight. the ratio of the hydrogen partial,pressure at 2000 The insults-oi various operations carriedout and 4000c. f..b. is approximately 11.1.

TABLE 1 .RunNo. (JP/4W9.

Test period No. Feedstock 1 2 3 4 5 3 Hours on stream'since regeneration10 27 75 001 115 Operating Conditions Catalyst-charge, vol .m1..'fiatalyst charge; wt g..

Direction of flow Average catalyst bed temperature.

' Reactor pressure .;p. s.

v./v.f/hg..

Gas make c. r. b1.

Liquid Product Percent wt. on feedstock-.. 100. 99. 4 '99. 2 98. 3 100.3 100.0 'Specllic gravity, l60 F O. 8545 0. 8485 0. 8480 0. 8475 0.84750. 8480 0.8520 .Gravity 34. l 35. 3 35. 4 35. 5 35.5 35. 4 34. 0

Distillation B. P 0.. 239 165 143 170 189 171 100.5 2%"V0l: 0.. 245 218229 236 234:5 238 M1 57 Vol. 0.. 256 250 251 251 250 '258 255. 5

l 0 V0]. C. 267. 5 264. 5 263 '263. 5 264 267 266. 5

40%Vol. 0.. 287 285. 5 286 286 284 283 '287 '-50g V01.-@ 0.. .291. 5290. 5 292 291 290 289 291 60 q Vol. .C- 297 290 298 296. 5 296 296 206.5

% Vol. 0.. 302 302. 5 305 302.5 303 301. 5 302 V01. 0.. 308. 5 310 311311 311 310 308 V01 0.. '321. 5 323 324 324 326 322. 5 '320 B P 0.. 349352 550. 5 350. 5 353 347 349 otal distillate .zpercent v01 99 99. 5 9999. 5 99 99 99 Residue-Hess .-per-cent vol 1 0.5 1 '0. 5 1 1 1 lphurpercent wt. 1. 00 0. 598 0. 566 0. 607 0. 674 0; 674 '0. 701

,8u1phur; removal -;per-cent- TABLE 2 Run No. (JP/I99 Test period No.Feedstock 1 2 3 4 5 Hours on stream since regeneration 12 52 OperatingConditions Catalyst charge ..vol. m1 988 Average catalyst bedtemperature.. F.- Reactor pressure -.p. s. i. ga.. 75 75 75 75 Spacevelocity- .v./v./hr 2. 00 1. 98 2. 00 1. 98 1. 98 Recycle gas rate..."0. f. 2,020 2, 030 2, 020 2,030 2, 030 Recycle gas density (a1r=1) 0. 220.24 0. 24 0.25 0. 24 Recycle gas mol. per cent Hz (=l:1%) 83 83 81. 583 Gas make ..c. f. 50. 5 36. 3 28. 1 23. 6 19. 9

Liquid Product Per cent wt. on feedstock 100. 0 99. 8 99. 7 99. 7 99. 599.9 Specific gravity, 60l60 F... 0.8520 0. 8460 0.8470 0. 8460 0.84750. 8460 Gravity .-A. P. L- 34. 6 35. 8 35.6 35.8 35.5 35.8

Distillation I (3.. 224 126 147 158 182 0.. 252 219 199. 5 219. 5 235221 0-. 263 239 241 243. 5 252 247 V 1. 0.. 272 260 260 264 264 261 0-.278. 5 274 274 274.5 277 275. 5 0.. 283. 5 280 280 280 281 281.5 C 288.5 285 285 286 287 285. 5 C 292 290 289 290. 5 291 290. 5 C 297 294. 5294. 5 295. 5 296 295. 5 0.. 304 300 300 301. 5 301. 5 301. 5 0-. 310308. 5 308. 5 308. 5 309 309 0.. 320 319 319 320' 321 320. 5 P 0-- 357.5 34B. 5 349 352 353 353 Total distillate" -.per cent voL. 99 99 99 9999 99 Residue+loss ..per cent voL. 1 1 1 1 1 1 per cent wt.. 1. 00 0.448 0.457 0.473 0.498 0. 519 -per cent- 55. 2 54. 3 52. 7 50. 2 48. 1

TABLE 3 Run N0.-OP/.i7/100 Test Period No. Feedstock 1 2 3 4 i 5 Hourson stream since regeneration 14 24 32 40 50 Operating ConditionsCatalyst charge ..vol. ml.. Catalyst charge..- wt. g

N0. of regenerations. Total life of catalyst. .hr Direction of flowAverage catalyst bed temperature. F.. Reactor pressure .p. s. 1. gaSpace vel0c1ty -.-v./v./hr.- Recycle gas rate ..c. f. b..

Recycle gas density (eir=1) Recycle gas 11101. per cent H2 (=\=1% GasMake ..c. t. b..

Liquid Product Per cent wt. on feedstock Specific gravity, 50l60 F-Gravity --A. P. L.

per cent vol. per cent vo1.

awn:

TABLE 4 Run NO. P/47/97 Test period No. Feedstock 1 2 3 Hours on streamsince regeneration 11 21 29 Operating Conditions Catalyst charge ..vol.m1.. Catalyst charge wt. g. No. of regenerations Total life ofcatalyst... Direction of flow Average catalyst bed temperature. Reactorpressure Space velocity. Recycle gas rate. Recycle gas density (a1r=1)Recycle gas mol. per cent H2 (i1%) Gas make v.

Liquid Product Per cent wt. on feedstock 100. 0 99. 8 99. 8 Specificgravity, 60/60 F I 0.8510 0. 8455 0. 8450 0.8455 Gravity 34. 35. 9 36. 035. 9

Distillation I. B. P 235 118 122 121 2% vol. 258 211 213. 5 215 5% vol.265 241 244 244. 5 vol. 271 256 260 260. 5 vol. 278 271. 5 272. 5 272vol. 283 279 278. 5 278. 5 vol. 288 284. 5 284. 5 283. 5 vol. 292. 5289. 5 290 289 vol 297. 5 294. 6 295 295 vol. 303. 5 301. 5 301. 5 30].5 vol. 311 309 309. 5 310 vol 323. 5 "321. 5 322 I 323 F. B. P 349.5350. 5 350. 5 350. 5 Total distillate. ..pcr cent vol-. 99. 5 99 99 99Resldue+loss Qper cent vol.. 0. 5 1 1 -1 Sulphur ..per cent wt.. 1. 010. 245 0.270 02 294 Sulphur removal -.per cent 75. 7 73. 3 70. 9

TABLE 5 Run No. C'P/47/96 Test period No. Feedstock l '2 3 Hours onstream since regeneration 11 '27 '61 Direction of flow Average catalystbed temperature... Reactor pressure Space velocity.

Recycle gas rate. Recycle gas density (air- Recycle gas mol. per cent Hz(:1: 1% Gas Make Liquid Product Per cent wt. on feedstock Specificgravity 60l60 F.. Gravity Distillation I. B. P 0-- 2% vol. C.. 5% vol.0.. 10% vol. .C 20% vol. 0-- 30% vol. 0.- 40% vol. C. 50% vol. 0.. 60%vol. 70% vol. 0.- 80% vol. 0-- 90% vol. 0.. F. B. P 0-- Totaldistillate. per cent vo1.. Residue-H055 --per cent vo1-.

Sulphur per cent wt..

Sulphur removal -.per cent.-

TABLE 6 Run No. CP/47/108 Test period No. Feedstock 1 2 3 4 5 Hours onstream since regeneration... 10 20 30 40 50 Operating ConditionaCatalyst charge vol. mL. 988 Catalyst charge..- wt. g.- 942 N o. ofregenerations- 16 Total life of catalyst- 1, 560 1, 570 1, 580 1, 590 1,600 Direction of flow. Downward Average catalyst bed 1; 800 800 801 800801 Reactor pressure 101 100 100 100 Space velocity 1 96 1. 97 1. 97 197 Recycle gas rate 2, 080 2, 050 2, 040 2, 040 2, 020 Recycle gasdensity 0. i 0. 0. 28 Recycle gas mol. per cent H 80. 80. 5 79 Gas make69.1 47.4 35 4 28.9 21 7 Liquid Product Per cent wt. on feedstock- 100.099.0 98. 9 99. 1 99 5 Specific gravity, 60/60 F 0 855 0 847 0. 848 0.8470.8485 0.8490 Gravity 34 0 35 6 35.4 35.6 35 3 2 Distillation 237 105108 118 114 120 253 8 195 217 204 228 261 229 5 237 240. 5 238 5 246 2682 254 254. 5 258 259 276 5 270 269 273 272 273.5 282 5 277 5 278 279 278280.5 287 283 283. 5 284 285 285. 5 291 5 288 291 288 5 290 290.5 296293 296 294 5 295 5 295.5 303 299 301 800 301 5 301 311 5 307 308 308. 5310 308 323 319 320 321 320 320. 5 351 5 353 353 353. 5' 352 350. 5 .percent vol.- 99 5 99 5 99. 5 99.5 99 5 99.5 Residue-Hess per cent vo1 0.50 5 y 0.5 0.5 0 5 0.5 Sulphur; per cent wt 0. 983 0. 325 0.375 0. 421 0.441 0. 470 Sulphur removal per n 65. 9 61. 9 57. 2 55.1 52. 2

TABLE 7 Run No. (JP/4W2" Test period No. Feedstock 1 2 3 4 5 Hours onstream since regeneration 10 29 50 78 Operating Conditions Catalystcharge. .vol. ml.. 1, 003 Catalyst charge... Wt. g. 85%

hr.. 1, 630 l, 640 v 1, 649 1, 670 1, 698 Downward Average catalyst bedtemperatur F" 760 759 760 761 760 Reactor pressure p. s. 1. ga.. 100 100100 100 Space velocity v./v./hr 2.03 1.99 1 98 2.00 1. Recycle gas ratert. b 1, 980 2, 000 2, 010 1, 990 2, 010 Recycle gas density (air=1) 0.0. 25 0. 27 Recycle gas mol. per cent H1 (:!=1%) 81. 5 81. 5 79 Gas m kc f. 26.4 12.8 7.9 1.7 N11 Liquid Product Per cent wt. on feedstock 100.0 97. 2 99. 6 100 0 99. 7 9 9 Specific gravity 60/60 F. 0.8535 0. 84700. 8455 0. 8470 0. 8485 0 8490 Gravity .311. P. L- 34. 3 35. 6 35. 7 35.6 35. 3 35. 2

Distillation I. B. P 0.. 234 2% vol. 249 5% vol. 262 10% vol. 270. 5 20%vol. 278 30% vol. 283. 5 vol. 288. 5 vol. 294 vol. 298 vol 305. 5 29%29-2 0 v0 F. B. P 353. 5 Total distillate per cent vol 99 Reaiduc+1ossper cent vol 1 Sulfur ..per cent wt 1. 00 0 457 0 507 Sulfur removal percent 54. 3 49 3 TABLE 8 Catalyst charge 1,000 ml. (849 g) Direction offlow Downward Test period No. Feed 1 2 3 4 5 6 7 8 9 10 11 Hours onstream 6 16 36' 46 56 66 76 86 98 I 106 116 Operating Conditions LiquidProduct Per cent wt. on feed Specific gravity 60/60 F Distillation LVB.P --Z 8.- 2 5%..- a 0.. 10%. 0.. 0.. 0.. 0.- 0-- 0.. 0.. 28 5 8" F.life. 0: 0: Total distillate. vol. per cent Residue vol. per cent.- Lossvol. per cent Bromine number. Flash point F.- Sulphur --per cent wt..0.00 0. 369 0.279 0. 333 0. 349 0. 366 0.294 0; 343 0:401 0.436 0.4580.497 Sulphur removal -.per cent.. 63.1 72.1 66. 7 65.1 63.4 70. 2 65. 759.0 56.4 54.2 40. 6

TABLE 9 Catalyst charge 880 ml. (763 g) Direction of flow 1 DownwardNumber of regenerations 2 Test period No. Feed 1 3 j 3' 4 5 6 7 Totalcatalyst life-hours 269 284 309 334 359 384 396 Clgtalyst hours onstream since regenera- 10 25 50 137 Operating Conditions Averagecatalyst bed temperature... F.- 788 792 789 780 789 V 784 785 Reactorpressure ..p. s. i. ga.. 100 100 100 100 100 98 95 Space vclocity....v./v./hr 2 32 2 25 2 26 2.27 2 35 2 24 2 45 Recycle gas rate ..c. f. b1, 960 2,080 2,010 2,000 1, 930 2,030 1,850

Recycle gas density (air =1) Recycle gas mol. percent H: (:1: 1%)

Gasmake .b.. b0, 26 '9 517 Liquid Product g g ii? iidfiIIIIIII 59352 092623 093232 0. 363 $5433 $3532 $3536 0. 52532 Distillation .vol. percent.- 1 1 1 1 1 1 1. 5

Loss ..vo]. per cent..-

S lphur ..wt. per cent..- 0. 99 0.193 0.279 0.363 0. 447 0.480 0. 5250.557

Sulphur removal --per cent.- 80. 5 71.8 63. 3 54. 8 51. 5 47. 0 43. 7

' TABLE 10 Catalyst charge 8801111. (763 g) Direction of flow DownwardNumber of regenerations I 3 Test period No. Feed 1 2 3 4 5 6 7 Totalcatalyst lite-hours... 405 421 446 478 496 521 546 Catalyst hours onstream since regeneratlom. 10 78 100 125 150 I Operating ConditionsAverage catalyst bed temperature F-. 780 781 780 781 781 782 782 Reactorpressure go. 105 103 103 105 105 105 105 Space velocity... /v.ll1r. 11 1. 1 1.07 1.11 1 11 Recycle gas rate ..c. 1. b. 4, 490 3, 850 4, 1204, 260 4, 260 4, 080 4, 080 Recycle gas density (air=1) 0 0. 28 0 0. 260 0. 28 Recycle gas mol. per cent H2 (=l=1%) 84 83 78 82 80. 5 78 .Gasmake 0 f. b-. 95 76 51. 5 32. 4 22. 6 15 8 11. 6

' Liquid Produd Per cent wt. on feed 100; 00 99. 08 99.15 98. 92 99. 6996. 25 99.40 100. 36 Specific gravity l60 F 0. 854 0.8485 0.8465 0. 84700. 8475 0.8480 0.8495 0. 8495 Distillation g lB. P 0.. 237 112 108 106113 120 120 127 0.- 350 352 5 348. 5 348 348 349 350 351. 5 .vol. percent. 98. 5 99 98.5 98. 6 98. 5 98.5 99 98. 5 Residue .vol. percent.- 1. 5 1 1. 5 1. 5 1. 5 1. 5 1 1. 5 Loss..' ..vol. per cent.

Sulphur ..per cent wt.- 0. 99 0.301 0. 208 0. 186 0. 293 0. 316 0. 3460. 367 Sulphur removal. per cent.. 69. 6 78. 9 81. 2 70. 4 68. 1 .65. 162. 9

TABLE 11 Catalyst charge 7 990 ml. 903 g) Direction of flow DownwardNumber of Regeneratlons 5 Test period No. Feed 1 2 3 4 5 6 Totalcatalyst lite-hours. 757 772 797 I 822 847 857 Catalyst hours on streamsince regeneration 10 25 50 100 Operatma Condition:

Average catalyst bed temperatur F-. 781 780 779 784 782 783 Reactorpressure .-p. s. 1. ga.. 103 104 103 101 101 102 Space velocity.v./v./hr 0. 993 0. 989 0. 978 0. 978 0. 97B 0. 978 Recycle gas rate l.b 2, 010 2, 020 2, 040 2, 040 2, 040 2, 040 Recycle gas density (air=1).0. 288 0. 250 0. 251 0. 285 0. 280 0.280 Recycle gas, 1110]. per cent H1(=1=1%) 83 .82 82 77 78 78 Gas make 0 I. b-. 92. 5 78 v 36. 8 22. 6 11.3 7. 5

Liquid Product Per cent welght on feed 100. 00 98. 93 95. 28 98. 91 101.51 99. 04 Specific gravity, 60l60 F 0. 854 0. 8475 0.8475 0. 8480 0.8480 0.8475 0.8490

Distillation 128 105 108 113 129 116 190 192. 5 225 230 205 234 233 6237. 6 244 5 249 5 243 258 255 265. 5 260 261 259 271 269 5 271. 5 271.5 274 5 272 5 277 6 280 278. 5 280 5 279 282 282 5 285. 5 283 286 284287 5 287 289. 5 289 290 288 5 2 291 295 295 295 5 294 300 298 5 301 301301 5 300 308 308 308. 5 309 309 308 5 322 322 320 821 321 5 320 350 3495 852. 5 350 350 350 347 98. 5 99 99 5 99. 5 99 ..Vol. per cent.- 1.5 11 0 5 0.5 0 5 0 5 Loss. Vol. per cent Sulphur --per cent wt. 0. 99 0.287 Sulphur removal I per cent I 71.0

Swims The process according to the invention mayv be operated by settingthe pressure in the desul- I phurisation zone at a predetermined leveland thereafter withdrawing from the system gas in excess of thatrequired to maintain the predetermined pressure. In this case, there isa continuous make of hydrogen indicating that the hydrogen produced inthe dehydrogenation reaction is not being fully utilised in thedesulphurisation reaction.

A method of operation which enables a greater degree of desulphurisationtobe achieved; the on-stream hours for a product of given sulphurcontent to be increased, and the hydrogen produced in thedehydrogenationreaction to berIully utilised in thedesulphurisation reaction, consistsin-recycling the hydrogen-containing gases to the desulphurisation zoneand allowing the pressure therein to riseto an equilibrium pressure atwhich the hydrogen evolved equals the hydrogen consumed.

With this method of operation; since 'it is convenient to recycle thegas at a constant rate by volume under-plant pressure, and in'view-otthe16 v..-/v./hr., a temperature of 780 F. and a fixed pressure of 100lb./sq. in., and excess gas beyond that required to maintain saidpressure vented from the system, the residual sulphur after 10 hours onstream was about 0.25% by weight and after 80 hours on stream was about0.35% by weight, whereas by allowing the pressure in thedesulphurisation zone to build up to an equilibrium pressure, theresidual sulphur in the product after 10 hours on stream was only about.05% by weight and after 80 hours on stream was just over 0.2%by weight.

It is believed that the greater degree of desulphurisation isattributable to the increased pressure but the equilibrium pressure doesnot exceed about 200 1b./sq. in. so that thecost ot the plant stillcompares favourably with that'o! TABLE 12 Run No. 02/47/127 TestPerlodNo.

Hours on stream since regeneration;

Operating Conditions:

Catalyst charge vol ml- Catalyst charge wt -..g N0 of regenerationsn-Total life ol catalyst. hr Direction 01 flow Average catalyst bedtemperature F.'. Reactor-pressure .p..s.-i. ga-. Space velocityv./v./hr.. Recycle gas rate c. f. b Recycle-gas rate at-plantpressures... .c..l. 1)-.

Recycle gas density (am-=1) Recycle gas mol. per cent-Ha*'(:l:l%) Gasmake.

Liquid Product Residue-Hose;

Corrosion (Cu strip) Sulphur ..per cent wt" Sulphur removal; ..per cent.

Per cent wt. on feedstock fact that the plant pressure is varying, the,vol.-' ume of gas recycled to the autofining zone at'; standardconditions of temperature and pressure will therefore also vary.

The advantages to bederived from thismethod-fl 0! operation are clearly,brought out in the fol--- lowing results obtained when treating anIraqi gas oil containing 0.8% wt. of sulphur. V

When this feedstock was fpassed 'ito aqdesule 7 sults being given forcobalt molybdate onbauxite,

molydenum oxide on'alumina, molybdenum oxide onalumina impregnated withcobalt molybdate;

phurisation zone at .a space velociti of 2,0 and cobalt chromateonalumina.

TABLE 13 Molybde- Oobalt Cobalt num oxide Cobalt Molyb Molyb- Molybdeonalumina chrw Catalyst date on date on num oxide impregmate on IndianAmerican on alumina mated with alumina Bauxite Bauxite cobalt molybdatcFeedstock Iranian Gas Oil (1.0 per cent wt. sulphur) OperatingConditions Temperature. 11. 780 780 780 780 780 Pressure 1 p. s. 1. ga100 100 100 100 100 S ace velocity v./v./hr 2. 2.0 2.0 2.0 2.0 asrecycle SOF/B 4, 000 4, 000 4, 000 4, 000 4, 000

Liquid Product 50 hours on stream Per cent desulphurisation 48 51 20 3624 Gas make, SCF/B 24 19 9 10 12 We claim:

1. In a continuous process for the hydrocatalytic desulphurization of asulphur-andnaphthene-containing petroleum oil boiling substantially inthe gas oil range wherein the oil is contacted in vapor form in areaction zone at an elevated temperature and pressure in the presence ofhydrogen with a dehydrogenation-hydrogenation catalyst which is immuneto sulphur poisoning and combines activity for the dehydrogenation ofnaphthenes in said oil to aromatics with activity for the hydrogenationof organically combined sulphur in said oil to hydrogen sulphide, themethod of operating the process so that it will be self-supporting withrespect to the amount of hydrogen needed and produce a desulphurizedproduct oil having, except for lowered sulphur content, properties andboiling range substantially the same as the feedstock, comprising thesteps of passing the gas oil to be treated through said reaction zoneand contacting the gas oil therein with said catalyst and with hydrogenderived solely from the oil, maintaining a selected temperature in saidzone between about 750 F. to about 820 F. at which hydrogen iscontinuously produced from said oil, maintaining a selected pressure insaid zone between about 50 to about 200 lbs/sq. in. gauge, said selectedtemperature and pressure being correlated to provide, from thedehydrogenation of naphthenes contained in said oil, a net production ofhydrogen at least sufficient to maintain the pressure in said zonesubstantially constant, separating a hydrogen-rich gas mixture from thetreated gas oil, recycling said hydrogen-rich gas mixture to thereaction zone to constitute the whole of the hydrogen supplied to saidzone, the hydrogen recycle rate being sufficient to maintain thenecessary partial pressure of hydrogen in said zone, and recovering thedesired product oil.

2. A process according to claim 1, wherein the feedstock is passed tosaid reaction zone at a space velocity from between about 1 to 2v./v./hr., wherein the selected temperature is approximately 780 131,wherein the selected pressure is approximately lbs/sq. in. gauge, andwherein said hydrogen-rich gas mixture is recycled to the reaction zoneat a rate between about 2000 to 4000 cu. ft./bb1. of feedstock.

3. A process according to claim 1, wherein the catalyst consists of thecombined oxides of cobalt and molybdenum supported on alumina.

PATRICK DOCKSEY. FREDERICK WILLIAM BERTRAM PORTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,325,034 Byrns July 27, 19432,392,579 Cole Jan. 8, 1946 2,393,288 Byrns Jan. 22, 1946 2,398,919Byrns Apr. 23, 1946 2,417,308 Lee Mar. 11, 1947 2,440,236 Stirton Apr.27, 1948

1. IN A CONTINUOUS PROCESS FOR THE HYDROCATALYTIC DESULPHURIZATION OF ASULPHUR-ANDNAPHTHENE-CONTAINING PETROLEUM OIL BOILING SUBSTANTIALLY INTHE GAS OIL RANGE WHEREIN THE OIL IS CONTACTED IN VAPOR FORM IN AREACTION ZONE AT AN ELEVATED TEMPERATURE AND PRESSURE IN THE PRESENCE OFHYDROGEN WITH A DEHYDROGENATION-HYDROGENATION CATALYST WHICH IS IMMUNETO SULPHUR POISONING AND COMBINES ACTIVITY FOR THE DEHYDROGENATION OFNAPHTHENES IN SAID OIL TO AROMATICS WITH ACTIVITY FOR THE HYDROGENATIONOF ORGANICALLY COMBINED SULPHUR IN SAID OIL TO HYDROGEN SULPHIDE, THEMETHOD OF OPERATING THE PROCESS SO THAT IT WILL BE SELF-SUPPORTING WITHRESPECT TO THE AMOUNT OF HYDROGEN NEEDED AND PRODUCE A DESULPHURIZEDPRODUCT OIL HAVING, EXCEPT FOR LOWERED SULPHUR CONTENT, PROPERTIES ANDBOILING RANGE SUBSTANTIALLY THE SAME AS THE FEEDSTOCK, COMPRISING THESTEPS OF PASSING THE GAS OIL TO BE TREATED THROUGH SAID REACTION ZONEAND CONTACTING THE GAS OIL THEREIN WITH SAID CATALYST AND WITH HYDROGENDERIVED SOLELY FROM THE OIL, MAINTAINING A SELECTED TEMPERATURE IN SAIDZONE BETWEEN ABAOUT 750* F. TO ABOUT 820* F. AT WHICH HYDROGEN ISCONTINUOUSLY PRODUCED FROM SAID OIL, MAINTAINING A SELECTED PRESSURE INSAID ZONE BETWEEN ABOUT 50 TO ABOUT 200 LBS./SQ. IN. GAUGE, SAIDSELECTED TEMPERATURE AND PRESSURE BEING CORRELATED TO PROVIDE, FROM THEDEHYDROGENATION OF NAPHTHENES CONTAINED IN SAID OIL, A NET PRODUCTION OFHYDROGEN AT LEAST SUFFICIENT TO MAINTAIN THE PRESSURE IN SAID ZONESUBSTANTIALLY CONSTANT SEPARATING A HYDROGEN-RICH GAS MIXTURE FROM THETREATED GAS OIL, RECYCLING SAID HYDROGEN-RICH GAS MIXTURE TO THEREACTION ZONE TO CONSTITUTE THE WHOLE OF THE HYDROGEN SUPPLIED TO SAIDZONE, THE HYDROGEN RECYCLE RATE BEING SUFFICIENT TO MAINTAIN THENECESSARY PARTIAL PRESSURE OF HYDROGEN IN SAID ZONE, AND RECOVERING THEDESIRED PRODUCT OIL.